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[FEATURE]: Filter which tools are loaded from MCP servers (includeTools/excludeTools) #4469

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opened 2026-02-16 17:43:52 -05:00 by yindo · 2 comments
yindo commented 2026-02-16 17:43:52 -05:00
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Originally created by @marcusquinn on GitHub (Jan 8, 2026).

Originally assigned to: @thdxr on GitHub.

Feature hasn't been suggested before.

  • I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Problem

MCP servers often expose many tools, but agents typically need only a subset. Currently, enabling an MCP loads all its tools into the context window, adding significant token overhead.

Example: The chrome-devtools MCP provides 26 tools (~17k tokens). A UI preview agent might only need 4 of them (~1.5k tokens).

Proposed Solution

Add includeTools and/or excludeTools to MCP configuration:

{
  "mcp": {
    "chrome-devtools": {
      "command": "npx",
      "args": ["-y", "chrome-devtools-mcp@latest"],
      "includeTools": ["navigate_page", "take_screenshot", "new_page", "list_pages"]
    }
  }
}

Or with glob patterns:

{
  "mcp": {
    "github": {
      "includeTools": ["create_*", "list_*"],
      "excludeTools": ["*_dangerous_*"]
    }
  }
}

Per-Agent Override

Combined with per-agent MCP enabling, this allows fine-grained control:

{
  "mcp": {
    "chrome-devtools": {
      "enabled": false,
      "includeTools": ["navigate_page", "take_screenshot", "new_page", "list_pages"]
    }
  },
  "agent": {
    "ui-preview": {
      "mcp": {
        "chrome-devtools": { "enabled": true }
      }
    }
  }
}

Prior Art

Amp recently shipped this feature: Lazy-load MCP with Skills

Their implementation uses a companion mcp.json file per skill. The approach proposed here integrates with OpenCode's existing centralized config pattern.

Benefits

  • Token savings: Load only needed tools (17k → 1.5k in the chrome-devtools example)
  • Reduced confusion: LLM sees only relevant tools
  • Backward compatible: No includeTools = all tools (current behavior)

Related Issues

  • #7269 - Subagent list filtering (complementary - filters subagents, not MCP tools)
  • #6024 - Provider/model-specific MCPs (complementary - when to load MCPs)
  • #7362 - Tool descriptions as skills (similar goal, different approach)

Contribution

Happy to submit a PR for this if the approach is acceptable. We're tracking this in aidevops and can implement a workaround in the meantime, but native OpenCode support would be cleaner.

Originally created by @marcusquinn on GitHub (Jan 8, 2026). Originally assigned to: @thdxr on GitHub. ### Feature hasn't been suggested before. - [x] I have verified this feature I'm about to request hasn't been suggested before. ### Describe the enhancement you want to request ## Problem MCP servers often expose many tools, but agents typically need only a subset. Currently, enabling an MCP loads **all** its tools into the context window, adding significant token overhead. **Example:** The [chrome-devtools MCP](https://github.com/anthropics/anthropic-quickstarts/tree/main/mcp-servers/chrome-devtools) provides 26 tools (~17k tokens). A UI preview agent might only need 4 of them (~1.5k tokens). ## Proposed Solution Add `includeTools` and/or `excludeTools` to MCP configuration: ```json { "mcp": { "chrome-devtools": { "command": "npx", "args": ["-y", "chrome-devtools-mcp@latest"], "includeTools": ["navigate_page", "take_screenshot", "new_page", "list_pages"] } } } ``` Or with glob patterns: ```json { "mcp": { "github": { "includeTools": ["create_*", "list_*"], "excludeTools": ["*_dangerous_*"] } } } ``` ## Per-Agent Override Combined with per-agent MCP enabling, this allows fine-grained control: ```json { "mcp": { "chrome-devtools": { "enabled": false, "includeTools": ["navigate_page", "take_screenshot", "new_page", "list_pages"] } }, "agent": { "ui-preview": { "mcp": { "chrome-devtools": { "enabled": true } } } } } ``` ## Prior Art Amp recently shipped this feature: [Lazy-load MCP with Skills](https://ampcode.com/news/lazy-load-mcp-with-skills) Their implementation uses a companion `mcp.json` file per skill. The approach proposed here integrates with OpenCode's existing centralized config pattern. ## Benefits - **Token savings**: Load only needed tools (17k → 1.5k in the chrome-devtools example) - **Reduced confusion**: LLM sees only relevant tools - **Backward compatible**: No `includeTools` = all tools (current behavior) ## Related Issues - #7269 - Subagent list filtering (complementary - filters subagents, not MCP tools) - #6024 - Provider/model-specific MCPs (complementary - when to load MCPs) - #7362 - Tool descriptions as skills (similar goal, different approach) ## Contribution Happy to submit a PR for this if the approach is acceptable. We're tracking this in [aidevops](https://github.com/marcusquinn/aidevops) and can implement a workaround in the meantime, but native OpenCode support would be cleaner.
yindo commented 2026-02-16 17:43:52 -05:00
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@github-actions[bot] commented on GitHub (Jan 8, 2026):

This issue might be a duplicate of existing issues. Please check:

  • #3756: MCP tool blocking not working - agents can still see and access disabled tools
  • #2953: [feature request]: ability to dynamic turn on mcp server for specific agent
  • #4525: [FEATURE]: Allow per-project MCP enabled/disabled overrides
  • #5373: [FEATURE]: Allow to enable MCP on a per-agent basis
  • #6024: Provider/model-specific MCPs (related feature request you mentioned)
  • #7269: Reduce token overhead: Task tool injects all subagent descriptions into system prompt (shares token optimization goal)

Feel free to ignore if none of these address your specific case.

@github-actions[bot] commented on GitHub (Jan 8, 2026): This issue might be a duplicate of existing issues. Please check: - #3756: MCP tool blocking not working - agents can still see and access disabled tools - #2953: [feature request]: ability to dynamic turn on mcp server for specific agent - #4525: [FEATURE]: Allow per-project MCP enabled/disabled overrides - #5373: [FEATURE]: Allow to enable MCP on a per-agent basis - #6024: Provider/model-specific MCPs (related feature request you mentioned) - #7269: Reduce token overhead: Task tool injects all subagent descriptions into system prompt (shares token optimization goal) Feel free to ignore if none of these address your specific case.
yindo commented 2026-02-16 17:43:52 -05:00
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@marcusquinn commented on GitHub (Jan 8, 2026):

Thanks for flagging these! After reviewing:

Issue Status What it addresses How #7399 differs
#3756 Closed Bug: disabled tools still visible Bug fix, not feature
#2953 Open Enable/disable MCP per agent All-or-nothing - entire MCP on/off
#4525 Closed Per-project MCP overrides Project-level, still all-or-nothing
#5373 Closed Per-agent MCP enable/disable Same as #2953 - entire MCP
#6024 Open Provider/model-specific MCPs When to load MCPs, not which tools
#7269 Open (mine) Subagent list filtering Filters subagents, not MCP tools

The gap this issue fills:

All existing issues address enabling/disabling entire MCP servers. None address filtering which tools within an MCP are loaded.

Example: chrome-devtools MCP has 26 tools. With existing features, I can:

  • Enable it globally (26 tools, ~17k tokens)
  • Disable it globally (0 tools)
  • Enable it per-agent (still 26 tools)

With includeTools, I could load only 4 specific tools (~1.5k tokens) - a 91% token reduction while keeping the functionality I need.

This is complementary to per-agent MCP enabling (#2953, #5373) - you'd use both together for maximum control.

@marcusquinn commented on GitHub (Jan 8, 2026): Thanks for flagging these! After reviewing: | Issue | Status | What it addresses | How #7399 differs | |-------|--------|-------------------|-------------------| | #3756 | Closed | Bug: disabled tools still visible | Bug fix, not feature | | #2953 | Open | Enable/disable MCP per agent | **All-or-nothing** - entire MCP on/off | | #4525 | Closed | Per-project MCP overrides | Project-level, still all-or-nothing | | #5373 | Closed | Per-agent MCP enable/disable | Same as #2953 - entire MCP | | #6024 | Open | Provider/model-specific MCPs | When to load MCPs, not which tools | | #7269 | Open (mine) | Subagent list filtering | Filters subagents, not MCP tools | **The gap this issue fills:** All existing issues address enabling/disabling **entire MCP servers**. None address filtering **which tools within an MCP** are loaded. Example: chrome-devtools MCP has 26 tools. With existing features, I can: - Enable it globally (26 tools, ~17k tokens) - Disable it globally (0 tools) - Enable it per-agent (still 26 tools) With `includeTools`, I could load only 4 specific tools (~1.5k tokens) - a 91% token reduction while keeping the functionality I need. This is complementary to per-agent MCP enabling (#2953, #5373) - you'd use both together for maximum control.
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Reference: anomalyco/opencode#4469
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